Spark plug structure



June 27, 1944. l L. A HYLAND '2,352,481

SPARK PLUG STRUCTURE Filed July l, 1929 2 Sheets-Sheet 1 77z 4? P g4 5 34 253@ 30 QR J 2747453 sy f A s June 27, 1944. L, A. HYLAND 2,352,481

SPARK PLUG STRUCTURE Filed July 1, 1929 2 shets-sheei 2 IN VEN TOR.

A TTORNEY Patented June 27, ld@ v 2,352,481 eraan rana s'ranc'rnaa Delaware Application duly l, 1929, Serial No. $5,241

(Cl. 12S-169) 66 Claims.

This invention relates to ignition apparatus for internal combustion engines, and more particularly to improvements in spark plug struc-l tures.

One of the objects of the present invention is to provide' a. novel spark plug which is so constructed as to be particularly adapted for use in aeroplane engines.

Another object of the invention is to provide a combined spark plug and cable connection which may be readily installed and disassembled for inspection and repair.

Another object is to provide a spark plug embodying novel means for maintaining the center electrode in operative position.

Another object is to provide a `combined spark plug and cable connection embodying novel shielding means whereby the plug is adapted for use on engines operated in proximity to electrical apparatus, such as radio receiving sets.

A further object is to provide a structure of the above character which is not only shielded to prevent electrical interference, but is also moisture-proof.

Other objects include the provision of a shielded plug which is rugged and dependable in operation, and which is so constructed that its functions as a charge igniting device are not impaired; to provide novel means for detachably connecting the cable to the center electrode of the plug; and to provide means for angularly adjusting the ignition wire or cable relative to the spark plug body.

Several embodiments of the invention are illustrated in the accompanying drawings, wherein like reference characters refer 'to like parts throughout the several views, but it is to be understood that the drawings are for purposes of illustration only and are not designed as a denition of the limits of the invention, reference being had for this purpose to the appended claims. In the drawings:

Fig. 1 is an axial sectional view of a spark plug structure embodying the present invention;

Fig. 2 is a side elevation of the structure shown in Fig. 1;

Figs. 3 and i are sectional views taken on the lines 3-3 -and 4 4 respectively, of Fig. 1;

Fig. 5 is a side elevation, partly in section, of another embodiment of the invention;

Fig. 6 is a detailed view showing a portion of the sparkl plug in section, and illustrating details of the clamping or latch mechanism shown in Fig. 5; and

Fig. 7 is an axial sectional view of still another embodiment of the invention.

Referring more particularly to Figs. l to 4, inclusive, the spark plug structure embodying the present invention comprises a bodyy portion or shell t, which carries a grounded electrode 9. and which is exteriorly threaded at the lower end thereof. to facilitate its insertion in the cylinder wall Iii of an internal combustion engine. Centrally disposed within body portion t is a core carrying a center electrode il which is surrounded by a thin tube I2 of compressible insulating material, such as mica. Adjacent its lower end, the center electrode is enlarged to provide an an nular shoulder I3 against which the lower end of tube I2 abuts. The shoulder i3 also acts as a support for a series of annular mica washers I4, the upper one of said washers being engaged by -a cone-shaped, hollow sleeve I5 and the walls of thel opening in the latter having engagement with tube I2. Surrounding sleeve l5 and in engagement therewith is a cap or gland I8 which is threaded into the upper end of body portion 8, a washer I1 being interposed between the lower end of the gland and a suitable shoulder in said body portion to form a gas-tight joint therebetween. The upper end or shell I8 of gland I6 is formed as a barrel to provide a hollow cylinder or casing which is interiorly lined with a thin tube I9 of insulating material, such as mica, with the lower end of theA sleeve resting on an annular shoulder 20 formed in the gland. The shoulder 2G supports a stack of annular insulating washers 2i which surrounds the tube I2 and is surrounded by the sleeve i9, the washers preferably being formed of mica. Tube I2, washers 2i, and tube I9 form a continuous insulator or body which extends from the upper'end of cylinder yIll to a point closely adjacent the lower end of electrode Il. 1

Novel means are provided for retaining the center electrode II, washers I4, sleeve I5, and washers 2l in operative relation to gland I6 and body portion B. For this purpose the upper portion of center electrode Il is provided with a central longitudinally extending recess 22, and the upper end of said electrode. is of reduced diameter to receive a. washer 23 which may be formed of metal and which fits vsnugly within insulating tube I8. The upper tubular end of center electrode II is rolled or beaded over into engagement with the upper end of washer 23 whereby the center electrode and the elements associated therewith are securely clamped and held, between shoulder I3, shoulder 20 and washer 23.

As is clearly shown in- Fig. l, the upper end of the tubular` portion of gland I6 and the upper end of insulating tube I9 extend -above washer 28 to form a recess, pocket or socket for receiving the lower arm 24 of a head or cap in the form of an elbow 25 that is preferably formed of high grade insulating material, such as porcelain.

A The upper arm 26 of the elbow or insulating bushing 25 isprovided centrally with a circular bore 21 into which extends the end of a cable 28 provided with flexible insulation 29. Secured as by means of solder or in any other suitable manner to the inner end of cable 28 is a terminal in the form of a metal cap 8,0, which may be provided with a recess 3|` to receive the extremity of cable 28.

- Novel means are provided for electrically connecting cable 28 -to the center electrode II. In the form shown, a metal rod 32 forms an outlet with, and slidably extends into the elongated recess 22 in the upper end of, center electrode II and the extremity of said rod is longitudinally slotted and slightly sprung so that a good electrical connection is formed with the center electrode. 'I'he lower arm 24 of insulator 25 is pro-v vided with a circular bore or recess 83 having a 4diameter slightly larger than the outer diameter of rod 32 in order tovpermit ready assembly of the parts. The upper end of bore 35 opens into bore 21 closely adjacent the inner end of the latter, and the upper end of rod 3'2 extends through an openlng in metal cap 30. If desired, the upper end of the rod may be slotted to form a spring-like connection with cap 80 similar to the connection provided with the center. electrode, but preferably said end is threaded into an opening in cap 38, as shown at 34. It will be seen that after cable 28, 29, with cap 30 attached thereto, is introduced into bore 21, rod 32 is passed upwardly through bore 33 and threaded into the opening in cap 30 whereby a strong mechanical connection is provided for cable 28. 'I'he lower arm of elbow 25 is now insertedin the upper end of the cylinder I8, whereupon the slotted end of rod 32 is forced into recess 22 and the electrical connection between the cable and center electrode is completed.

In accordance with the present invention it is desirable to provide a shielded structure, and it is therefore necessary to surround insulating member 25 with a metal coating or covering. For this purpose a sheath or rigid metal shell 3'5 is preferably provided for enclosing elbow 25. The metal shield or elbow may be die-cast around the insulator elbow, electrodeposited thereon, or formed v in any other suitable manner, but care should be taken to prevent too close a fit between the metal elbow and the insulator elbow in order to avoid undue strains being imposed upon the latter when the plug is in use. The inner diameter of the lower ann 38 of the metal shield is greater than the outer diameter of arm 24 of the insulator elbow and also of the cylinder I8, whereby the lower arm 38 telescopically and closely en gages said cylinder when the'lower arm 24 of the insulator elbow is inserted in the upper end of 'cylinder I8. This construction provides an annular space 31 adjacent the upper end of cylinder I8 which serves to break up the capillary action of water or oil which may seep along the engaging surfaces of the cylinder and elbow, whereby a liquid-proof joint is formed. Particular attention is called to the fact that the, lower arm 38 of metal elbow 35 extends downwardly beyond the lower end of arm 24 of the insulatorl elbow whereby said arm 24 is relieved of all strainsA resulting from pressures applied to the structure. In the form shown the outer end oi the upper arm of elbow 85 is provided with an interior shoulder 38- which abuts against the outer end of arm 26 of the insulator elbow 25. Said 5 metal elbow is provided adjacent said shoulder with a laterally extending portion or hollow tension of reduced diameter for a purpose to be described hereafter. Novel means are provided for detachably connecting elbows 2'5 and 35 to cylinder I8 whereby assembly and repair of the'parts may be readily effected, and said means are preferably so formed that the elbows may be rotated relative to cylinder I8 in order that cable 28, 29 may be angularly adjusted relative to the spark plug body. Angular adjustment of .the cable is desirable in order to avoid sharp bends. whereby the installation of the structure is facilitated and damage to. insulation 29 is prevented. In the form shown. the 20 connecting means is of the lbottle cap type embodying a ring 39 which is rotatably disposed around cylinder I8 and is adapted to engage the lower surface of a collar 49, which is welded or otherwise suitably secured to the outer surface 2h of cylinder I8 substantially in the plane of washer 23. Secured tov and extending upwardly from ring 3 9 is a pair of arms 4I (Fig. 4) to the ends o f which is pivoted a lever 42. Intermediate the curved free end of lever 4 *2 and the points of atl tachment of said lever to arms 4I there are pivotally connected the lower ends of a bail 43 which extends around and is adapted for clamping engagement with the upper surface lof elbow 35. Preferably the latter is provided with a lug 44 which is engaged by the bight of the .bail when the latter is in clamping position;

When elbow 35 is lin telescoping engagement with cylinder I9 and lever 42 is in the raised position shown in Fig. 1, bail 43 is swung into engage- 40 ment with the upper surface of elbow 35 and,due

to the resiliency of the parts, lever 42 may be swung downwardly to the dotted line position in Fig. lv (the full line position of Fig. 2) to lock the parts in operative relation. By this .arrangement the cable is readily attached to or detached from center electrode II to provide for inspection of the parts and to permit angular adjustment of the cable relative to cylinder I8. The parts may be so proportioned that cable 28, 29, elbows 25 and 35, and rod 32 may be angular-ly adjusted relative to cylinder I8 when the latch or securing mechanism is in locked position.

It is necessary in order to provide a shielded ignition system to shield cable 28, 29 throughout its length, and means must be provided for forming a proper and serviceable connection between the cable shield and metal elbow 35. Preferably, a flexible sheathing of woven Wire 45 is employed for the cable 28, 29, and the present invention embodies novel means for detachably connecting said sheathing to elbow 35. To this end a light metal, cup--shapedl member 49, which islongitu-` dinally slotted adjacent one end thereof to provide a plurality of 'spring arms 41, is positioned on the flexible shield of the cable. 'I'he extremity of shield 45 is expanded around the reduced portion of elbow 35 to form a telescopic joint, as shown at 48 in Fig. 1. Cup 49 is thenslid along the sheathing 45 until arms 41 are forced into clamping engagement with an annular groove suitably formed in the outer surface of the reduced portion of the metal elbow. By a proper proportionins of the annular groove a very strong "connection can be provided between flexible shield 15 45 and metal elbow 35, and this connection coacts with rod 32 to retain cable 28, 29 in operative position-relative to the center electrode il. Particular attention is called to the act'that the cable insulation 29, which is usually a rubber composition, is protected from the high temperatures set up in the structure in the zone immediately adjacent to and above washer 23.

In Figs. and 6 there is illustrated another embodiment of the invention wherein the elbow clamping means.comprises a rotatably mounted ring 99 which carries a pair of diametrically disposed and laterally projecting pins 50 on which is pivotally mounted a lever 5I. A ball 52 formed of a dat strip of metal and adapted to engage the walls of a recess 53 formed in the upper surface of the metal elbow 54 is pivotally connected to lever 5l. 'Ihe pivotal connections between bail 52, lever 5I, and ring 99 are so disposed that the lever is swung upwardly when moved into clamping position with the free end of said lever underneath the overhanging upper arm of the elbow. A This arrangement insures against accidental movement of the lever to non-locking -position, but provides for ready detachment of the cable. The parts may be so proportioned as to permit angular adjustment of said cable even though the lever be in locking position.

As shown more clearly in Fig. 5, the flexible cable shield is expanded around the reduced end 59' of elbow 54, and shield and cable are mechanically bonded to said elbow by winding several turns of wire 55 around the expanded portion of shield 45. Preferably the wrapped wire is soldered to form a good connection.

Another embodiment of the invention is illustrated in Fig. 'I wherein a spark plug body 56 carries a. grounded electrode 51. A center electrode 58 is mounted in an insulator 5.9 which is preferably formed of porcelain and is retainedv in operative position in body 56 by means of a removable sleeve 69. The upper end 59a of insulator 59 is of tubular form to provide a conical chamber or pocket 6I above the center electrode. Extending down into this chamber is the lower arm 62 of an insulator elbow 63 which is shielded by means of a metal elbow 59. The inner diameter of the lower arm 65 of metal elbow 6d is such as to permit telescopic engagement of said lower arm with the upper end of sleeve 60, and the parts are held in operative relation by means of a split steel ring 65 adapted to extend into annular grooves in lower arm 65 and sleeve 66, said grooves being in registry when the parts are in normal assembled position.

A cable connecting member 61 projects centrally through the lower arm of insulator elbow 53 and is retained in position in said arm by being threaded into a metal sleeve or washer 68 inserted or threaded into a suitable recess in the lower end of the arm. The upper end of conductor member 61 is sharply pointed to pierce the insulation 29 of the ignition cable 28 and make electrical contact with said cable. The shielding 45 o said cable is suitably secured in the groove 41 of reduced extension 49 of elbow 6B, as by a retaining member shown in section in Fig. 'I and in elevation in Fig. 2. If desired, the parts may be so proportioned that the lower end or screw head of connecting cable member 51 is separated from the upper end of center electrode 58 whereby an extra. gap is provided to insure that the plug will re, even thoughthe electrodes are` fouled.

There is thus provided a novel spark plug Astructure which is particularly adapted for use in high compression engines and engines operated in proximity to radio apparatus. The shield is combined with the plug body in such a manner that the parts may be readily installed, and disd assembled for inspection and repair. Gland it and body portion 8, though separately formed in the embodiments of the invention illustrated, coact' to form a continuous metal shield which is in telescopic engagement with the continuous shield 35, 65. A portion of the former is rigid and extends below .the lower end of the insulator elbow to relieve the latter of strains, while the portion 45 is preferably iiexible to facilitate the handling of the cable and its connectlonwith the power source. It will be understood, how ever, that any suitable form of shield may be provided for the cable.

A strong electrical and mechanical connection is made between the cable and the center electrode of the plug, but the cable is always angularly adjustable and this without the necessity.

for releasing the clamping means. The center' electrodeof the plug is so mounted as to be retained in operative position at all times and to insure a gas-tight joint around said electrode.

In actual use the plug structure constituting the subject matter of the present invention has been found emcient and dependable. Various changes may be made in the details of construction, and 80 certain parts may be used without others. Reference will accordingly be had to the appended claims for a denition of the limits of the invems tion.

What is claimed is:

1. Means for connecting a spark plug cable and electrode having a recess in the upper end thereof, comprising an insulator, provided with arecess, surrounding said cable, a cap carried by `the end vof said cable, and a rod in electrical (0 engagement with said cap, the lower end of the rod extending into said rst named recess.

2. In apparatus of the class described, a. spark` plug body, a center electrode therein, a metal elbow secured to said body and having a reduced portion, insulating means in said elbow, a cable extending into the elbow, means for electrically connecting said' cable and electrode, a metal shield for said cable, and a cup for detachably connecting the cable shield with the reduced portion of the metal elbow.

3. Apparatus of the class described including a spark plug body having a hollow cylindrical portion, a metal elbow having the lower arm thereof in telescopic engagement with said cylindrical portion, an insulator elbow in the metal elbow and having the lower arm thereof extending into said cylindrical portion, whereby an annular space is provided adjacent the upper end o lary' action, current carrying means extending 16 ing detachable engagement with said electrode of the cylindrical portion for interrupting capii-J and cap, and means for rotatably connecting said insulator with the body of the plug.

6. A shielded spark plug structure for internal combustion engines comprising a body portion terminating in a hollow cylinder at the upper end thereof, a center electrode in said body portion. means forming a continuous insulator which surrounds the center electrode, said means terminating at its upper end in the piane of the upper end of the hollow cylinder and at its lower end near the lower'extremity of the center electrode, insulator member extending into the open upper end of said insulating means, a cable extending into the insulator member, means extending through a portion of the insulator member for operatively connecting the cable to the center electrode, a continuous metallic shieldfor the insulator member and cable, a portion of said shield having telescopic engagement with said hollow cylinder and another portion of said shield being flexible to permit bending of the cable, and

clamping means for detachably connecting said shield and hollow cylinder.

7. In combination, a sparkvplug body having a continuous metallic surface terminating at the upper end in a cylindrical portion, a metal shield surrounding said upper end, an electrode centrally disposed in said body portion, a cylindrical insulator surrounding said center electrode, an elbow formed of insulating material and having the lower arm thereof extending into the cylindrical portion of the plug, said elbow having a bore in the upper arm thereof, an insulated cable extending into said bore, means extending through the lower arm of said elbow for electrically connecting said cable and center electrode, and a metallic sheathsurrounding said cable and in overlapping electrical engagement with said shield.

8. In combination with an insulated cable, a spari: plug having a cylindrical portion at the upper end thereof, an insulator -elbow having its lower arm extending into said cylindrical .portion, the upper arm of the elbow being provided with a bore into which the cable extends. means extending through the lower arm of said insulator elbow for electrically connecting said cable and the center electrode of said plug, and rotatable means for detachably connecting said elbow and plug body whereby the cable may be removed from or angularly adjusted relative to the body of said plug.

9. Means for operatively connecting a spark plug cable with a spark plug electrode comprising an insulator member, a needle-like member extending through the insulator member for establishing electrical connection between the cable and o ne of the terminals of the spark plug, and a metallic sleeve threadedly engaging both said needle-like member and insulator member for retaining said needle-like member in operative lposition, said needle-like .member having a screw head serving as the electrical connection betweenl said cable and terminal, and also constituting the means whereby said needle-like member and cable are operatively connected prior to complete assembly of the plug.

l0. A terminal connector for a spark plug having, a body structure of insulating material substantially in theform'of an elbow with one portion of said elbow having a rod member extending centrally therethrough with a contact formed on one end thereof in engagement with the central electrode of said spark plug, and means for prior to connection with said ucomprising a member having portions extending substantially at right angles one to the other. one of said portions being recessed to receive the end of an ignition wire, the other of said portions carrying an adjustable screw threaded member arranged to engage the end of said ignition wire, said screw threaded member having a contact on its extremity for establishing an electrical connection with the center electrode of the spark D ug.

12. In combination .with a spark plug body, a center'electrode therein, insulating means interposed between the electrode and b ody and adapted to maintain said electrode in operative position, said body and insulating means being so formed as to provide a pocket above the upper end of the center electrode, a shielded insulator member having a portion thereof projecting into said pocket, a shielded cable extending into a recess in said insulator member, and means for establishing an electrical'connection between the center electrode and cable.

13. A shielded spark plug structure for internal combustion engines comprising a body portion terminating in a hollow cylinder at the upper end thereof, a, center-electrodein said body portion, means forming a continuous insulator which surrounds the center electrode, an insulator member extending into the open upper end of -said insulating means, a cable extending into the insulator member, `a continuous metallic shield ior the insulator member, a portion of said l shield having engagement with said hollow cylinder, a second ilexible shield surrounding the cable, and clamping meansfor detachably connecting said first shield and hollow cylinder.

14. A shielded spark plug and conductor comprising a casing formed of three overlapping sections, resilient means adapted to hold' two of `said sections in contact with each other, means for securing said shielded conductor to one of said sections, and means integral with the other two sections for securing said other twosections to each other.

15. Fastening means for a protecting cap of spark plugs comprising a member connected to the sparkplug in a manner permitting relative angular displacement of said member and plug,

and spring means mounted in said member and engaging the cap.

16. Fastening means-for a protecting cap of spark plugs comprising a member connected to the spark plug in a manner permitting relative angular displacement oi said member and plug and a spring vclamp having its ends mounted in said member and an intermediate portion adapted to engage the cap.

17. In a sparll' plug of the type having a cylinder engaging shell carrying one electrode and a shielded conductor electrically connected to the other electrode, the combination with said conductor and shell of a shield having a cylindrical portion secured at its lower end by direct,

locking contact with said shell, and having a second portion embracing the shielded conductor. and means for holding said two portions in engagement with eachother.

18. The method oi? assembling a spark plug or the self-shielding type which comprises the steps of separately assembling the cylinder engaging securing the opposite enciof the rod member 1n outer metallic shell. the center electrode and the parts supporting said center electrode and also separately assembling the cable receiving portion of the plug. said last named assembling process including the step or applying a metallic coating to the entire outer surface of the *cable receivingportion or Y the plug. then inserting the cable within said vcable receiving sub-assembly in a position such as to cause its metallic covering to contact said'ilrst-named metallic coating, then inserting a current conducting element in said cable receiving sub-assembly, and operatively connecting saidelement and cable, and nallyv bringing both sub-assemblies into operative connection, one with the otherl 19. Fastening means i'or a protecting cap Vof a spark plug comprising a member surrounding a portion of the spark plug which is disposed beneath said cap and spring means having its tallic shell, so as to cause registry therebetween, the extent or the registry being sumcient to automatically maintain the current path between said conductor and plug.

25. The method ci assembling a shielded spark I.

a path between said conductor and plug.

ends mounted on said member and engaging the cap, said cap and spring ,means being angularly displaceable in relation to the plug to permit the protecting cap to iace in any one of a plurality of directions as desired. c

20. Fastening meansfor a protecting cap of a sparkplug comprising a member surrounding a portion of the spark plug which is disposed beneath said cap and a clamp having its ends mounted on said member and engaging the cap, said cap and clamp being angularly displaceable in relation to theplug to permit the protecting cap to face in any one of a plurality ofdirections as desired.

2l. Fastening means for a protecting cap of a spark plug comprising an annular member surrounding a portion ofthe spark plug which is disposed beneath said cap and a retaining clamp having its ends secured by said annular member and adapted for engagement intermediate its ends with said cap.

22. Fastening means for a protecting cap for a spark plug comprising an apertured member surrounding a portion of the spark plug which is disposed beneath said cap and a clamping bail bent inwardly at its endsl to enable each of said ends to engage in one of said apertures, said bail having an intermediateportion engageable with the top of said cap.

23. The method of assembling a shielded spark plug which comprises the steps of making two separate sub-assemblies, one of which includes the cylinder engaging outer metallic shell, the center electrode and the parts supporting said center electrode, and the other of which includes the cable receiving portion of the plug, said last named sub-assembling process also including the step oi inserting the cable within said cable receiving sub-assembly in a position such as to automatically complete the current path from said cable to said center electrode when the two sub-assemblies above described are brought togather, and finally bringing said two sub-assemblies together in such a manner that one of the shielding elements of one of the sub-assemblies has engagement with a shielding element of the other sub-assembly, the extent of the registry there-between being sufficient to. automatically maintain the current path between the cable and the center electrode.

24. The method of assembling a shielded spark plug which includes the step of inserting a current conductor through an opening in one part of the shielding casing, and also the step of fitting said shielding part into its proper position with respect to the cylinder engaging outer me- 26. In the manufacture and assembly of spark plugs of the self-shielding type. the step of applying a metallic coating to the entire outer surface of the cable receiving yportion of the plug;

27. In the manufacture and assembly of spark plugs of the self-shielding type, the stepv` of applying a metallic coating to the entire outer surface of the cable receiving portion o the plug, also the step of inserting said cable through an opening in said cable receiving portion of the plug, and the further step of inserting a second current conductor through a secondopening, and securing said second conductor in current` conducting relation to saidv cable.

28. ln combination with a spark plug including a metal shell, and a shielded conductor therefor disposed with its longitudinal axis at an angle to the longitudinal axis of the plug, an insulating cover for a portion of said conductor, a device for preventing radiation of electrical energy therefrom comprising a casing formed of complementary sections, and means adapted to hold said sections in contact with each other, with a portion'of one of the sections tting about said insulating cover.

29. In combination with a spark plug body, a center electrode therein, insulating means interposed between the electrode and body and adapted to maintain said electrode .in operative position, said insulating means being so formed as to provide a pocket above the upper end of the center electrode, a shielded insulator member having a portion thereof projecting into said pocket, a shielded cable extending into a recess in said insulator member, and means for establishing an electrical connection between the center electrode and cable, the shields of said cable and said insulator being electrically connected with said body.

30. In apparatus of the class described, a spark y plug body, a center electrode therein, a metal elbow secured to said body and having a reduced portion, solid insulating means in said elbow, in intimate contact in the wall thereof, a cable extending into the elbow, means for electrically connecting said cable and electrode, a metal shield forvsaid cable, and means for detachably connecting the cable shield with the reduced portion of the metal elbow to provide an'electrical connectionto ground through said elbow.

31. In combination, a spark plug comprising a i metallic cap and a stem having an outlet, a conductor connecting to said stem at the outlet, a porcelain elbow seated insaid cap and enclosing said outlet and a metallic coating intimately encasing said elbow and grounded through said CBD.

6 .H said outlet and 4a metallic coating enclosing said conductor and a-metallic coating on said elbow electrically connected with said metallic cap, said coatings being in. the form of a thin sheath. 83. In combination. a spark plug, comprising a metallic cap and a vertical stem having an outlet,- a conductor having a connection with saidstem at the outlet, a porcelain elbow mounted on said cap and enclosing said outlet and providing for the i'ree movement o! said connection therein and a thin metallic coating on said conductor and a thin metallic coating enclosing said elbow, said coatings being electrically connected with said metallic cap.

34. In a spark plug. a metallic body shell, an electrode carrying core mounted therein, a head carrying a conductor part for connection with said core electrode, said head having `an external metallic shield for seating on said metallic body shelland forming a close .ioint therewith, and clamping means releasably holding the body shell and head in said assembled relation.

35. In a spark plug, a metallic body shell, an

electrode carrying core mounted therein, a headcarrying a conductor part for connection with said core electrode, said head having an external metallic sheld for rotatably seating on said metallic body shell and forming a close Joint-therewith, and means releasably holding the body shell and head in said assembled relation, and permitting relative rotation oi' the head and body shell when assembled.

36. In a radio shield for spark plugs, a shielding cap adapted to be positioned over a spark plug comprising a metal shell, a body of dielectric material within the shell, said body, having a lateral opening to receive a conductor and said body being formed withV a circular recess in alignment with the upper end of a spark plug, and a contact means carried by lthe dielectric body and adapted to engage the spark plug, said contact means being adapted to project into the lateral opening to contact a conductor.

37. Apparatus of the class described compris- 4ing in combination a spark plug body having an electrode, a cable connected to said electrode, a metallic casing extending substantially the length of said electrode, a metallic cap cooperating with said casing to enclose and shield said electrode and cable, means including a bail for 4securing said cap to said casing, and means in contact with said casing and cap and substantially filling the space between said casing and cap and said electrode and cable for insulating said casing and cap from said electrode and cable.

38. In combination with a spark plug having a metallic casing and a radio shielded cable there- :,asadsi .t e body oi dielectric material within said then having a portion oi' its surface in intimate cony tact with the shell, a portion or said dielectric body extending into said hollow extension to form a lining therefor, said dielectric body beingprovided with a bore to receive a conductor and contact means carried by the dielectric body.

41. In a radio shield for spark plugs, a cap to cover al plug, said cap comprising a metal shell and a body of dielectric material in the shell. a lateral extension on said shell and dielectric body provided with a bore to receive a conductor, a washer carried bythe dielectric body, and a contact means disposed through said washer, the lower end oi said contact means being adapted to be operatively disposed with respect to a spark plug and the upper end thereof being adapted to project into said bore to contact a conductor.

42. In a radio shield for spark plugs, a cap to cover a plug, said cap comprising a metal shell and a body of dielectric material intimately attached to said shell, said shell and body each having a lateral extensioniormed with a bore to receive a conductor and a contact means removably supported from said dielectric body, the upper end of said contact means being adapted to pierce the insulation oi' and make contact with a conductor in the bore and the lower end of said to the ground of the spark plug comprising, a

for, a shielding cap comprising a dielectric body disposed over the plus, said bodybeing provided with a bore to receive the spark plug cable, a conductor carried by said body to make contact with the spark plug and projecting into said bore and a metallic covering on said dielectric body contacting both the casing of the plug and the shielding oi' the spark plug cable.

39. In a radio shield for spark plugs, a cap to cover a plug, said cap comprising a body of dielectric material having a lateral extension, said extension being provided with an axial bore extending into the dielectric body, a conductor carried by said bodyproiecting into said bore and a metal cover around said dielectric body.

40. In a radio shield lfor spark plugs, a cap to cover a plug. said cap comprising a metal shell having a hollow extension on one side thereof,

metallic casing, an insulation material disposed within said casing and having one aperture to receive an insulated portion of said cable. and a further aperture adapted to receive a conductor part that constitutes a closure for said aperture and serving to electrically connect the plug and cable terminals, said insulation material having intimate contact with the walls of said casing.I

44. A shield for a spark plug adapted to electrically connect the shielding oi' a shielded cable to the ground of the spark plug comprising, a metallic casing, an insulation material disposed within said casing and having an aperture to receive an insulated portion of said cable, and a further aperture adapted to receive a conductor part that constitutes a closure for said aperture serving to electrically connect the plug and cable terminals, said insulation material having a relatively thin cross-section and being in intimate contact with the walls of said casing.

45. A shield for a spark plug adapted to elec trically connect the shielding ot a shielded cable to the ground of the spark plug comprising, a metallic casing, an insulation material disposed within said casing and having an aperture adapted to receive an insulated portion of said cable, and a further aperture to receive a conductor part, said conductor part serving to electrically connect the plug and cable terminals and said casing and insulation material cooperating to protect said cable.

46. A shield for a spark plug adapted to electrically connect the shielding of a shielded cable to the ground of the spark plug comprising, a metallic casing, insulation material disposed within air chamber between said plug terminal and said cable insulation.

47. -In combination, a spark plug comprising a metallic body shell and a core having a stemprovided with an outlet, an insulated conductor connectingto said stem at the outlet, a dielectric I member of. relatively thin cross-section inclosing angie' to the axis 'or the the plug being electrically connected to the groundedI portion o1' the plug, the insulation for -the conductor of said cable extending within the said outlet, a metallic coating intimately 'encas ingsaid member and grounded throughsaid shell, v and a member in intimate contact with said dielectric member forsegregating the insulation of said conductor from said outlet.

48. In combination, a spark plug comprising ametallic body shell and a core having 'a stem provided with an'outlet, a conductor connecting to said stem at the outlet, a metal casing inclos-y ing said connection and electrically spaced'therefrom a sumcient distance to prevent ash over and grounded to said shell, dielectric materiall of thin cross-section disposed within said casing and in intimate contact withthe walls thereof, and a member for segregatlng the insulation of said conductor from said outlet and in intimate contact with said dielectric.

49. A shield for a spark-plug adapted to elecplug shielding, the terminal of said conductor being connected tothe terminal 4 of said plug, in-

sulation material disposed within said plug shielding and around said cable, said insulation serving to electrically separate said shielding and cable-plug-terminal connection and having sur face contact with said shielding and meanscontacting with said insulation material for inclosing the cable insulation to protect the same.

53. In a spark plug, a threaded shell-having a grounded electrode at its inner end, and the'outer end of which shell is internally threaded: a tubular member having a threadedv portion engaging said internally threaded shell part, and which member extends beyond the outer end' -of said shell; van'electrode vwithin said tubular member and extending part way only 'along thelength thereof; an insulating tube within said tubular trically connect the shielding of a shielded cable to the ground of the spark plug comprising, a metallic casing, an insulation material disposed within said casing and so arranged as to provide with said plugsI dead air chamber, said insulation material having one aperture to receive an insulated portion of said cable, and a further aperture adapted to receive a conductor part that constitutes `a closure for said aperture and serving to electrically connect the. plug and cable terminals, said insulation material having intl.- mate contact with the walls of said casing.

50. In a spark-plug having a body and a central spindle insulated from the body, the combination of a metal barrel with insulation liningextending upward from the body labove the upper end of the spindle yto provide a socket for the insertion of an insulated high-tension conductor into electrical connection with said spindle, .a

connection through which the conductor is passed and which has detachable connection with said barrel, and insulating means about the portion of the insulated conductor within said socket,

- tween said `terminal and the outer end of said electrode, and the ends of which conductor contact the said last mentioned parts.

54. In a spark plug, a threaded shell having a grounded electrode at its inner end', andthe outer end of which shell is internally threaded; a tubular member having a threaded portion engaging said internally threaded shell part, and which member extends beyond the outer endV of said shell and is reduced in diameter so as to provide a thin wall portion beyond said .outer end; an

electrode within said tubular member and extending part way only along the length thereof an insulating tube within said tubular member and surrounding said electrode and extendingv to said insulating means being unitarily associated V with the conductor and in contact with said connection.

51. A shielded spark plug and electrical conductor cable for suppressing radio and other electrical disturbances comprising, a shielding for the plug and a shielding for the cable secured together near one end of said plug, said shielding including angularly related sections to enable said cable to extend at approximately a right angle to the axis of the plug, the shielding for the plug forming a part of the grounded portion of the plug, the insulation for the conductor of said cable extending within the plug shielding, the terminal of said conductor being electrically con nected to the terminal of said plug, and means Within the plug shielding for inclosing the cable insulation at the cable terminal and to electrically insulate said plug shielding from saidterminal connection.

52. A shielded spark plug and electrical conductor cable for suppressing radio and other electrical disturbances comprising, a shielding for the plug and a shielding for the cable secured together near one end of said plug, said shielding including angularly related sections to enable said cable to extend at approximately a right the outer end of said tubular member; a metallic housing detachably secured to Athe outer end'of said tubular member; an insulating member'enclosed within said housing and having a bore disposed in line with said tubular member; a supply conductor extending into said housing and' insulating member andhaving a terminal in said bore; and a conductor within said tubular member and said v:bore and extending between said terminal and the outer end of said electrode,

and the ends of which conductor contact the said last mentioned parts.

55. A shielded spark'plugfor a radio receive equipped vehicle, comprising a metallic outer shell having an opening at the top thereof, an insulating body within said shell having a recess at the top portion thereof, an electrode extending4 through said body and terminating in said recess, a metallic recessed apertured cap through which an insulated electrical conductor may exltend attached to said shell at the opening thereof, and an insulating bushing seated'in said `cui in cooperative relation therewith and extending into the recess of the insulating body, said bushing snugly surrounding said conductor and the cooperation between said cap and said bushing forcing intimate contact between the end of the conductor and the terminal of said electrode when said cap is attached to said shell.

plug, the shielding forl 8' assasei through said body and terminating in said recess.

a metallic recessed apertured cap through which an insulated electrical conductor may extend detachably attached to said shell at the opening thereof, and an insulating bushing seated in said cap in cooperative relation therewith and extending into the recess of the insulating body, said bushing closely surrounding said conductor and the cooperation between said cap and said bushing insuring current conducting continuity between the end of the conductor and the terminal of said electrode when said cap it attached to said shell.

57. In combination with a spark plug, a shielding elbow comprising a metallic sheath in the form of an elbow, an insulator in the form of an elbow in said sheath, a conductor having a threaded portion slidably extending through a part of said insulator from one end thereoL'an insulated conductor slidably extending into the other end of said insulator at an angle to said nrst named conductor, and an internally threaded member secured to said insulated conductor and adapted to threadedly engage said threaded portion.

58. In apparatus of, the class described, an y elbow-shaped insulator having a bore therethrough, a conductor slidably extending into one end of said insulator, said conductor being threaded at the inner end thereof, a second conductor slidably extending into the other end of said insulator at an angle `to said ilrst named conductor, and internally threaded means secured to said second conductor and adapted to threadedly engage the inner end of said ilrst named conductor.

59. In a spark plug having a center electrode and a barrel extending above said electrode to form a socket, the combination therewith of a metallic shield,means for detachably connecting said shield to said barrel, an insulator in said shield having a portion extending into said barrel,- electric current conducting means extending into said insulator and having electrical connection .with said center electrode. an insulated conductor `slidably extending into the other end of said insulator and at an angle to said'conducting means, and means for detachably connecting the adjacent ends of said conductors together.

60. In a spark'plug having a center electrode andal barrel extendingabove said electrode to form a socket, the combination therewith of a metallic sleeve having a straight portion and an angularly directed portion, means for detachably connecting said sleeve to said barrel. an insulating liner in said`sleeve and extending into said barrel. a rigid conductor extending into the straight portion oi said liner and being electrically connected to said electrode. a iiexible conductor extending into said angularly directed portion of said liner, andmeans on said flexible conductor for threadedly engaging said rigid conductor. v f

61. In a spark plug having a center electrode and a barrel extending above said electrode to form a socket, the combination therewith of a metallic sheath, means fordetachably connecting said sheath to said barrel, an attaching means at the other end of said sheath. a shielding conduit detachably connected to said attaching means, an insulatoil in said sheath having a portion extending into said barrel andhaving a bore therethrough, an insulated conductor extending through said conduit into said insulator. a threaded member secured to said insulated.

conductor. and a conductor extending into the other end of said insulator and having threaded engagement with said threaded member, said last named conductor being electrically connected to said electrode.

62. In apparatus of the class described, a rigid insulator having a bore therethrough composed of angularly related sections, a rigid conductor extending into one section of said bore, 'a iiexible conductor extending into the other section of said bore, and means secured to said flexible conductor for threadedly engaging said rigid conductor within said insulator.

63. A spark plug shield comprising an L- shaped metallic casing having an insulating elbow integral therewith, said elbow in one arm of said casing being shaped to receive the spark plug cable and in the other arm to iit closely with the extending portion of the spark plug,-

in combination with means for securingsaid', casing to saidspark plug.

64. Means for shielding a spark plug and associated cable comprising a non-conducting elbow into one arm oi which said cable extends, the other arm being oi' suilicient thickness to fit closely with 'said plug, and a metallic elbow surrounding said ilrst named elbow and forming a permanently integrated single unit therewith.

65. A spark plug covering comprising an-L- shaped metallic sleeve and an insulatingelbow whose surface "conforms to the inner contour of said sleeve.

66. A spark plug covering comprising a metallic elbow and an L-shaped insulating sleeve permanently amxed to the inner surface 1ot said metallic elbow.

LAWRENCE A. HYLAND. 

